Array substrate for liquid crystal display device and method of fabricating the same

ABSTRACT

An array substrate includes first and second lines on a substrate and formed of a metallic material; a gate electrode connected to the first line; a gate insulating layer on the first and second lines and the gate electrode and including a groove exposing the substrate and positioned between the first and second lines; a semiconductor layer on the gate insulating layer and corresponding to the gate electrode; a data line crossing the first and second lines and on the gate insulating layer; a source electrode connected to the data line; a drain electrode spaced apart from the source electrode; a passivation layer on the data line, the source electrode and the drain electrode and including an opening, the opening exposing the gate insulating layer and the drain electrode; and a pixel electrode positioned on the gate insulating layer and in the opening and contacting the drain electrode.

This application is a Divisional Application of copending U.S. patentapplication Ser. No. 12/943,345 filed on Nov. 10, 2010, which claims thebenefit of Korean Patent Application No. 10-2009-0110704 filed in Koreaon Nov. 17, 2009, both of which are hereby incorporated by reference intheir entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD) deviceand more particularly to an arrays substrate being capable of preventingan electrical shortage problem and a method of fabricating the arraysubstrate.

2. Discussion of the Related Art

Recently, the LCD devices having characteristics of light weight,thinness and low power consumption are introduced. Among these LCDdevices, the LCD device including a thin film transistor (TFT) as aswitching element, referred to as an active matrix LCD (AM-LCD) device,has excellent characteristics of high resolution and displaying movingimages such that the AM-LCD device are widely used.

Generally, the LCD devices are fabricated by an array substrate process,a color filter substrate process and a cell process. In the arraysubstrate process, a TFT and a pixel electrode are formed on a firstsubstrate such that an array substrate is obtained. In the color filtersubstrate process, a color filter and a common electrode are formed on asecond substrate such that a color filter substrate is obtained. Then,in the cell process, a liquid crystal layer is interposed between thefirst and second substrates.

FIG. 1 is an exploded perspective view of the related art LCD device. InFIG. 1, The LCD device includes first and second substrates 12 and 22,and a liquid crystal layer 30. The first and second substrates 12 and 22face each other, and the liquid crystal layer 30 is interposedtherebetween.

The first substrate 12 includes a gate line 14, a data line 16, a TFT“Tr”, and a pixel electrode 18. The first substrate 12 including theseelements is referred to as an array substrate 10. The gate line 14 andthe data line 16 cross each other such that a region is formed betweenthe gate and data lines 14 and 16 and is defined as a pixel region “P”.The TFT “Tr” is formed at a crossing portion of the gate and data lines14 and 16, and the pixel electrode 18 is formed in the pixel region “P”and connected to the TFT “Tr”.

The second substrate 22 includes a black matrix 25, a color filter layer26, and a common electrode 28. The second substrate 22 including theseelements is referred to as a color filter substrate 20. The black matrix25 has a lattice shape to cover a non-display region of the firstsubstrate 12, such as the gate line 14 and the data line 16 on the firstsubstrate 12. A light leakage in the non-display region is blocked bythe black matrix 25. The color filter layer 26 includes first, second,and third sub-color filters 26 a, 26 b, and 26 c. Each of the sub-colorfilters 26 a, 26 b, and 26 c has one of red, green, and blue colors R,G, and B and corresponds to the each pixel region “P”. The commonelectrode 28 is formed on the black matrix 25 and the color filterlayers 26 and over an entire surface of the second substrate 22.

Although not shown, edges of the first and second substrates 12 and 22are sealed such that a leakage of the liquid crystal layer 30 isprevented. First and second alignment layers for controlling an initialarrangement of the liquid crystal molecules in the liquid crystal layer30 are formed on the first and second substrates 12 and 22,respectively. A polarizing plate is formed on at least one outer side ofthe first and second substrates 12 and 22. In addition, a backlight unitfor providing light is disposed under the first substrate 12.

When the TFT “Tr” is turned on by a signal through the gate line 14, asignal is applied to the pixel electrode 18 through the data line 16such that a vertical electric field is induced between the pixel andcommon electrode 18 and 28. As a result, the liquid crystal layer 30 isdriven by a vertical electric such that the LCD device can produceimages.

FIG. 2 is a plane view showing one pixel region of an array substratefor the related art LCD device. In FIG. 2, a gate line 55 and a dataline 80 are disposed on a substrate 51. The gate and data lines 55 and80 cross each other to define a pixel region “P”. A TFT “Tr”, which isconnected to the gate and data lines 55 and 80, as a switching elementis disposed in the pixel region “P”. In addition, a common line 59,which is formed of the same material and disposed on the same layer asthe gate line 58, is disposed on the substrate 51. The common line 59 isparallel to and spaced apart from the gate line 58.

The TFT “Tr” includes a gate electrode 57, a semiconductor layer 78, asource electrode 83 and a drain electrode 86. A pixel electrode 93 isconnected to the drain electrode 86 through a drain contact hole 90. Thepixel electrode 93 overlaps the common line 59 to form a storagecapacitor “StgC”.

As mentioned above, the common line 59 is disposed on the same layer asthe gate line 58. Namely, the gate line 58 and the common line 59 areformed by patterning a metal layer (not shown) on the substrate 51. Whenthere is a defect, for example, particles, on a patterning process,there is an electrical short problem between the gate line 58 and thecommon line 59. The electrical short problem is not remedied byfollowing processes, for example, a process of forming the semiconductorlayer 78, a process of forming the source and drain electrodes 83 and 86and a process of forming the pixel electrode 93.

To remedy the electrical short problem, a repair process for cutting theelectrical short portion by irradiating a leaser beam is required. Or,an additional mask process, which includes a step of forming aphotoresist (PR) layer, a step of exposing the PR layer, a step ofdeveloping the exposed PR layer, and a step of etching the metal layer,for removing the electrical short portion, is required. As a result, theproduction costs are increased and the production yield is decreasedbecause of the electrical short problem. The electrical short problemmay be generated not only the gate and common lines 58 and 59 but alsoother electric lines.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an array substrate foran LCD device and a method of fabricating the same that substantiallyobviates one or more of the problems due to limitations anddisadvantages of the related art.

An object of the present invention is to provide an array substrate foran LCD device being capable of preventing an electrical short problem.

An object of the present invention is to provide a fabricating processof an array substrate for an LCD device being capable of reducingproduction costs.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, anarray substrate for a liquid crystal display device includes first andsecond lines on a substrate and spaced apart from each other, the firstand second lines formed of a first metallic material; a gate electrodeconnected to the first line; a gate insulating layer on the first andsecond lines and the gate electrode and including a groove, the grooveexposing the substrate and positioned between the first and secondlines; a semiconductor layer on the gate insulating layer andcorresponding to the gate electrode; a data line crossing the first andsecond lines and on the gate insulating layer; a source electrode on thesemiconductor layer and connected to the data line; a drain electrode onthe semiconductor layer and spaced apart from the source electrode; apassivation layer on the data line, the source electrode and the drainelectrode and including an opening, the opening exposing a portion ofthe gate insulating layer and an end of the drain electrode; and a pixelelectrode positioned on the gate insulating layer and in the opening,the pixel electrode contacting the end of the drain electrode.

In another aspect of the present invention, a method of fabricating anarray substrate for a liquid crystal display device includes forming afirst line, and a second line and a gate electrode on a substrate, thefirst and second lines spaced apart from each other, the gate electrodeconnected to the gate line, the first line, the second line and the gateelectrode formed of a first metallic material; forming a gate insulatinglayer on the first and second lines and the gate electrode, an activelayer on the gate insulating layer and an impurity-doped amorphoussilicon pattern on the active layer, the gate insulating layer includinga grove, the active layer and the impurity-doped amorphous siliconpattern corresponding to the gate electrode, wherein the groove exposesthe substrate and is positioned between the first and second lines;forming a data line on the gate insulating layer and source and drainelectrodes on the impurity-doped amorphous silicon pattern, the dataline crossing the first and second lines, the source electrode connectedto the data line and spaced apart from the drain electrode; etching aportion of the impurity-doped amorphous silicon pattern using the sourceand drain electrode as an etching mask; forming a passivation layer,which is disposed on the data line, the source electrode and the drainelectrode and includes an opening exposing a portion of the gateinsulating layer and an end of the drain electrode, and a pixelelectrode on the gate insulating layer and in the opening, wherein thepixel electrode contacts the end of the drain electrode.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is an exploded perspective view of the related art LCD device;

FIG. 2 is a plane view showing one pixel region of an array substratefor the related art LCD device;

FIG. 3 is a plane view showing one pixel region of an array substratefor an LCD device according to the present invention;

FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3;

FIGS. 5A to 5D are plane views showing a fabricating process of an arraysubstrate for an LCD device according to the present invention; and

FIGS. 6A to 6L are cross-sectional views showing a fabricating processof an array substrate for an LCD device according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments,examples of which are illustrated in the accompanying drawings.

FIG. 3 is a plane view showing one pixel region of an array substratefor an LCD device according to the present invention, and FIG. 4 is across-sectional view taken along the line IV-IV of FIG. 3. FIG. 3 showsa gate line and a common line disposed adjacent to each other. On theother hand, two gate lines may be disposed adjacent to each other. Inthis case, a principle for preventing an electrical short is alsoapplied. A switching region, where a TFT as a switching element isformed, is defined in FIG. 4.

In FIGS. 3 and 4, a gate line 105 and a common line 109 along a firstdirection are disposed on a substrate 101. The common line 109 isadjacent to the gate line 105 and spaced apart from the gate line 105 bya distance. For example, the distance between the common line 109 andthe gate line 105 may be 7 to 12 micrometers. In addition, a gateelectrode 107, which is connected to the gate line 105, is disposed onthe substrate 101 and in the switching region TrA.

A gate insulating layer 113 is disposed on the gate line 105, the gateelectrode 107 and the common line 109. The gate insulating layer 113 hasa groove 116 of a bar shape. The groove 116 is disposed between the gateline 105 and the common line 109 and has a width smaller than thedistance between the gate line 105 and the common line 109. Namely, aportion of the substrate 101 between the gate line 105 and the commonline 109 is not covered by the gate insulating layer 113. A major axisof the groove 116 is parallel to the gate line 105. A minor axis of thegroove 116 has the width smaller than the distance between the gate line105 and the common line 109.

A data line 130 is disposed on the gate insulating layer 113 and crossesthe gate line 105 to define a pixel region P. A length of the major axisof the groove 116 is smaller than a distance between two adjacent datalines 130 such that the groove 116 does not overlap the data lines 130.In the switching region TrA, a semiconductor layer 128 including anactive layer 122 and an ohmic contact layer 125 is disposed on the gateinsulating layer 113. In addition, a source electrode 133 and a drainelectrode 136 is disposed on the semiconductor layer 128. The source anddrain electrodes 133 and 136 are spaced apart from each other. A centerportion of the active layer 128 is exposed through a space between thesource and drain electrodes 133 and 136. The exposed portion of theactive layer 128 serves as a channel. The source electrode 133 isconnected to the data line 130. The gate electrode 107, the gateinsulating layer 113, the semiconductor layer 128, the source electrode133 and the drain electrode 136 in the switching region TrA constitute athin film transistor (TFT) Tr.

FIG. 3 shows the channel of I shape. However, there is no limitation ina shape of the channel. For example, the source electrode 133 has a Ushape and the drain electrode 136 is inserted into the U shape such thatthe channel has a U shape. On the other hand, FIG. 3 shows the switchingregion TrA is positioned in the pixel region P. Alternatively, a portionof the gate line 105 serves as the gate electrode 107 such that theswitching region TrA is positioned on the gate line 105.

A passivation layer 142 is disposed on the TFT Tr and the data line 130.The passivation layer 142 has an opening 144 to expose an end of thedrain electrode 136 and the gate insulating layer 113 in the pixelregion P. The passivation layer 142 is disposed in the groove 116 of thegate insulating layer 113. As a result, the passivation layer 142 in thegroove 116 contacts the substrate 101.

A pixel electrode 153 is disposed in the opening 144 of the passivationlayer 142 and on the gate insulating layer 113. The pixel electrode 153contacts the end of the drain electrode 136. The pixel electrode 153overlaps the common line 109 with the gate insulating layer therebetweento form a storage capacitor StgC.

In the present invention, the groove 116 is formed between the lines,which are disposed at the same layer as and adjacent to each other. Evenif an electrical short problem, which resulted by a particle, isgenerated, the electrical short portion is removed when the groove 116is formed. Accordingly, the electrical short problem is never generated.

FIGS. 5A to 5D are plane views showing a fabricating process of an arraysubstrate for an LCD device according to the present invention, andFIGS. 6A to 6L are cross-sectional views showing a fabricating processof an array substrate for an LCD device according to the presentinvention. FIGS. 6A to 6L show a pixel region, a gate link region, agate pad region and a data pad region.

As shown in FIGS. 5A and 6A, a first metal layer (not shown) is formedon the substrate 101 by depositing a first metallic material such asmolybdenum (Mo), Mo-titanium alloy (MoTi), chromium (Cr), aluminum (Al)Al alloy (AlNd), copper (Cu) and Cu alloy. Alternatively, the firstmetal layer may have a multiple-layered structure by depositing at leasttwo of the first metallic material.

The first metal layer is patterned by a mask process to form the gateline 105, the common line 109, the gate electrode 107, a gate link line106 and a dummy metal pattern 110. The mask process includes a step offorming a photoresist (PR) layer, a step of exposing the PR layer, astep of developing the exposed PR layer to form a PR pattern, and a stepof etching the metal layer using the PR pattern. The common line 109 isadjacent to the gate line 105 and spaced apart from the gate line 105.The gate electrode 107 extends from the gate line 105 and is disposed inthe switching region TrA. The gate link line 106 is positioned at andconnected to an end of the gate line 105. The gate line 106 is disposedin the gate link region GLA. The dummy metal pattern 110 is positionedbetween the gate line 105 and the common line 109. The dummy metalpattern 110 is disposed at an inner area of the pixel region P. Namely,the dummy metal pattern 110 has a length smaller than a distance betweentwo adjacent data lines 130 to avoid overlapping the data line 130. Whenthe first metal layer has a double-layered structure or a triple-layeredstructure, each of the gate line 105, the gate electrode 107, the gatelink line 106, the common line 109 and the dummy metal pattern 110 has adouble-layered structure or a triple-layered structure.

Next, as shown in FIG. 6B, the gate insulating layer 113, an intrinsicamorphous silicon layer 120 and an impurity-doped amorphous siliconlayer 123 are stacked on the gate line 105, the gate electrode 107, thegate link line 106, the common line 109 and the dummy metal pattern 110by sequentially depositing an inorganic insulating material, intrinsicamorphous silicon and impurity-doped amorphous silicon. For example, theinorganic insulating material may includes silicon oxide or siliconnitride.

Next, a PR layer 180 is formed on the impurity-doped amorphous siliconlayer 123 by coating a PR material. The PR material has a negativeproperty such that a light-irradiated portion remains after developingprocess. Alternatively, the PR material having a positive property maybe used. In this case, a position of a transmitting area and a blockingarea are replaced by each other.

Next, an exposing mask 191 is disposed over the PR layer 180. Theexposing mask 191 includes a transmitting area TA, a blocking area BAand a half-transmitting area HTA. The half-transmitting area HTA hastransmittance less than that of the transmitting area TA and greaterthan that of the blocking area BA. The transmitting area TA has arelatively high transmittance, for example, about 100%, so that lightthrough the transmitting area TA can completely change the third PRlayer 283 chemically. The blocking area BA shields light completely. Thehalf-transmitting area HTA has a slit structure or a half-transmittingfilm so that intensity or transmittance of light through thehalf-transmitting area HTA can be lowered. For example, thehalf-transmitting area HTA has transmittance with a range between about10% and about 90%. The transmitting area TA corresponds to the switchingregion TrA. In other word, the transmitting area TA corresponds to thegate electrode 107. Namely, the transmitting area TA corresponds to aregion where the semiconductor layer 128 (of FIG. 4) will be formed. Theblocking area BA corresponds to an end of the gate link line 106 and thedummy metal pattern 110. The half-transmitting area HTA corresponds tothe other regions. The PR layer 180 is exposed through the exposing mask191.

Next, as shown in FIG. 6C, the exposed PR layer 180 is developed to formfirst and second PR patterns 181 a and 181 b on the impurity-dopedamorphous silicon layer 123. The first PR pattern 181 a corresponds tothe transmitting area TA of the exposing mask 191 (of FIG. 6B) and has afirst thickness. Namely, the first PR pattern 181 a corresponds to thegate electrode 107. The PR layer 180 (of FIG. 6B) corresponding to theblocking area BA of the exposing mask 191 is completely removed suchthat portions of the impurity-doped amorphous silicon layer 123 areexposed through the first and second PR patterns 181 a and 181 b.Namely, the impurity-doped amorphous silicon layer 123 over the end ofthe gate link line 106 and the dummy metal pattern 110 is exposed. Thesecond PR pattern 181 b corresponds to the half-transmitting area HTA ofthe exposing mask 191 and has a second thickness smaller than the firstthickness.

Next, as shown in FIG. 6D, a link contact hole 115 for exposing the endof the gate link line 106 and the groove 116 for exposing the dummymetal pattern 110 are formed through the gate insulating layer 113 bysequentially etching the impurity-doped amorphous silicon layer 123, theintrinsic amorphous silicon layer 120 and the gate insulating layer 113using the first and second PR patterns 181 a and 181 b as an etchingmask.

Next, as shown in FIGS. 5B and 6E, by performing an ashing process ontothe first and second PR patterns 181 a and 181 b (of FIG. 6D), thesecond PR pattern 181 b having the second thickness is removed such thatthe impurity-doped amorphous silicon layer 123 (of FIG. 6D) is exposed.At the same time, a thickness of the first PR pattern 181 a is reduced.However, since the first thickness of the first PR pattern 181 a isgreater than the second thickness of the second PR pattern 181 b, thereis a third PR pattern 181 c in the switching region TrA.

Next, the impurity-doped amorphous silicon layer 123 (of FIG. 6D) andthe intrinsic amorphous silicon layer 120 (of FIG. 6D) are etched usingthe third PR pattern 181 c to form the active layer 122 of intrinsicamorphous silicon on the gate insulating layer 113 and an impurity-dopedamorphous silicon pattern 124 of impurity-doped amorphous silicon on theactive layer 122. At the same time, the gate insulating layer 113 isexposed by etching the impurity-doped amorphous silicon layer 123 (ofFIG. 6D) and the intrinsic amorphous silicon layer 120 (of FIG. 6D). Asmentioned above, the link contact hole 115 for exposing the end of thegate link line 106 and the groove 116 for exposing the dummy metalpattern 110 are formed through the gate insulating layer 113.

Next, as shown in FIG. 6F, a stripping process is performed onto thethird PR pattern 181 c (of FIG. 6E) such that the third PR pattern 181 cis removed.

Next, as shown in 5C and 6G, a second metal layer (not shown) is formedon the impurity-doped amorphous silicon pattern 124, the gate insulatinglayer 113 and the dummy metal pattern 110 (of FIG. 6F) by depositing asecond metallic material such as molybdenum (Mo), Mo-titanium alloy(MoTi), chromium (Cr), aluminum (Al) Al alloy (AlNd), copper (Cu) and Cualloy. Alternatively, the first metal layer may have a multiple-layeredstructure by depositing at least two of the first metallic material.Since the gate insulating layer 113 has a groove 116 for exposing thedummy metal pattern 110, the second metal layer contacts the dummy metalpattern 110.

The second metallic material for the second metal layer may be same asthe first metallic material for the first metal layer. Or, the secondmetallic material may be etched by an etchant for the first metallicmaterial. For example, when the first metallic material is Al, thesecond metallic material is Al or Al alloy.

Next, a PR layer (not shown) is formed on the second metal layer. The PRlayer on the second metal layer is exposed and developed by a maskprocess to form a fourth PR pattern (not shown) corresponding to regionswhere the data line 130, the source electrode 133, the drain electrode136, a gate pad and a data pad. Namely, the fourth PR pattern isdisposed at a boundary of the pixel region P, the switching region TrA,the gate pad area GPA, the gate link area GLA and the data pad area DPA.The third metal layer at the other regions is exposed. Particularly, thesecond metal layer on the dummy metal pattern 110 is not coved by thefourth PR pattern.

Next, the second metal layer is etched using the fourth PR pattern as anetching mask to form the data line 130, the source electrode 133, thedrain electrode 136, the gate pad 138 and the data pad 137. The dataline 130 on the gate insulating layer 113 crosses the gate line 105 suchthat the pixel region P is defined. The data line 130 is connected tothe source electrode 133. The source and drain electrodes 133 and 136are disposed on the impurity-doped amorphous silicon pattern 124 andspaced apart from each other. One end of the impurity-doped amorphoussilicon pattern 124 is covered with the source electrode 133, and theother end of the impurity-doped amorphous silicon pattern 124 is coveredwith the drain electrode 136. The gate pad 138 is disposed in the gatepad area GPA. One end of the gate pad 138 extends into the gate linkarea GLA to contact the gate link line 106 through the link contact hole115. The data pad 137 is disposed in the data pad area DPA. The data pad137 is connected to one end of the data line 130.

When the second metal layer is etched, the dummy metal pattern 110 isalso etched such that the substrate 101 is exposed through the groove116. As mentioned above, since the second metal layer is formed of thesame material as the first metal layer or the material being etched byan etchant for the first metal layer, the dummy metal pattern 110 issimultaneously etched with the second metal layer. Accordingly, even ifan electrical short problem is generated between two adjacent lines,i.e., the gate line 105 and the common line 109, the dummy pattern 110on the substrate 101 is removed when the second metal layer is etchedsuch that the electrical short problem is never generated. In addition,an additional mask process for preventing the electrical short problemis not required.

Next, as shown in FIG. 6H, a portion of the impurity-doped amorphoussilicon pattern 124 (of FIG. 6G) exposed through a space between thesource and drain electrodes 133 and 136 is dry-etched such that theohmic contact layer 125 from the impurity-doped amorphous siliconpattern 124 is formed on the active layer 122. In addition, a centerportion of the active layer 122 is exposed. The active layer 122 and theohmic contact layer 125 constitute the semiconductor layer 128.

The gate electrode 107, the gate insulating layer 113, the semiconductorlayer 128, the source electrode 133 and the drain electrode 136 in theswitching region TrA constitute a thin film transistor (TFT) Tr.

Next, as shown in FIG. 6I, an insulating material layer 140 is formedover the substrate 101, where the data line 130 and the TFT Tr areformed, by depositing an inorganic insulating material such as siliconoxide and silicon nitride. A PR layer (not shown) is formed on theinsulating material layer 140. The PR layer is exposed and developed bya mask process to form a fifth PR pattern 183. A portion of theinsulating material layer 140, where the pixel electrode 153 (of FIG. 4)will be formed, is not covered by the fifth PR pattern 183. In addition,portions of the insulating material layer 140 at a center of the gatepad area GPA and a center of the data pad area DPA are not covered bythe fifth PR pattern 183. Namely, the fifth PR pattern 183 correspondsto the data line 130, the source electrode 133, a portion of the drainelectrode 136, the gate line 105, both sides of the gate pad area GPA,the gate link area GLA and both sides of the data pad area DPA.

Next, as shown in FIG. 6J, the exposed portions of the insulatingmaterial layer 140 are etched using the fifth PR pattern 193 as anetching mask to form an opening 144 in the pixel region P, a gate padcontact hole 145 in the gate pad area GPA and a data pad contact hole147 in the data pad area DPA. The other portions of the insulatingmaterial layer 140 under the fifth PR pattern 183 remains after theetching process to form a passivation layer 142. A portion of the gateinsulating layer 113 in the pixel region P is exposed through theopening 144. In addition, an end of the drain electrode 136 is exposedthrough the opening 144. The gate pad 138 is exposed through the gatepad contact hole 145, and the data pad 137 is exposed through the datapad contact hole 147. The other portions of the insulating materiallayer 140 under the fifth PR pattern 183 remains after the etchingprocess to form a passivation layer 142.

In this case, to completely remove the insulating material layer 140 onthe gate pad 138 and the data pad 137, the insulating material layer 140is over-etched. As a result, the passivation layer 142 has an under-cutshape with respect to the fifth PR pattern 183. Namely, the passivationlayer 142 has a width smaller than the fifth PR pattern 183. Asexplained below, because the passivation layer 142 has the under-cutshape, a lift-off process for forming a pixel electrode and removing thefifth PR pattern 183 can be processed by a single mask process.

Next, as shown in FIG. 6K, a transparent conductive material, forexample, indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), is depositedover the substrate 101, where the fifth PR pattern 183 is formed, toform a transparent conductive material layer 150, a pixel electrode 153in the pixel region P, a gate pad electrode 155 in the gate pad area GPAand a data pad electrode 157 in the data pad area DPA. The transparentconductive material layer 150 covers an upper surface and side surfacesof the fifth PR pattern 183. The pixel electrode 153 is disposed in theopening 144 to be disposed on the gate insulating layer 113. The pixelelectrode 153 contacts the end of the drain electrode 136 and overlapsthe common line 109 to form a storage capacitor StgC. Namely, theoverlapped portion of the common line 109, the overlapped portion of thepixel electrode 153 and the gate insulating layer between the commonline 109 and the pixel electrode 153 constitute the storage capacitorStgC. The gate pad electrode 155 contacts the gate pad 138 through thegate pad contact hole 145. The data pad electrode 157 contacts the datapad 137 through the data pad contact hole 147.

Each of the transparent conductive material layer 150, the pixelelectrode 153, the gate pad electrode 155 and the data pad electrode 157has a thickness smaller than the passivation layer 142. As mentionedabove, since the passivation layer 142 has the under-cut shape withrespect to the fifth PR pattern 183, there are discontinuous parts atboundaries between the transparent conductive material layer 150 andeach of the pixel electrode 153, the gate pad electrode 155 and the datapad electrode 157. As a result, portions of the fifth PR pattern 183 areexposed through the discontinuous parts. If each of the transparentconductive material layer 150, the pixel electrode 153, the gate padelectrode 155 and the data pad electrode 157 has a thickness greaterthan the passivation layer 142, the discontinuous parts are notgenerated.

Next, as shown in FIGS. 5D and 6L, the substrate 101, where the fifth PRpattern 183 (of FIG. 6K), the transparent conductive material layer 150,the pixel electrode 153 (of FIG. 6K), the gate pad electrode 155 and thedata pad electrode 157 are formed, is dipped into a stripping solutionsuch that the fifth PR pattern 183 (of FIG. 6K) is exposed to thestripping solution. Alternatively, a stripping solution may be sprayedonto the substrate 101. The stripping solution reacts a material of thefifth PR pattern 183 exposed through the discontinuation parts. Thestripping solution penetrates into an interface between the fifth PRpattern 183 and the passivation layer 142 such that an adhesive strengthbetween the fifth PR pattern 183 and the passivation layer 142 isweakened. As a result, the fifth PR pattern 183 is removed from thepassivation layer 142. At the same time, the transparent conductivematerial layer 150 on the fifth PR pattern 183 is also removed with thefifth PR pattern 183. The above process may be called as a lift-offprocess. The pixel electrode 153, the gate pad electrode 155 and thedata pad electrode 157 remain after the lift-off process.

In the present invention, the passivation layer 142, the pixel electrode153, the gate pad electrode 155 and the data pad electrode 157 areformed by a single mask process through the lift-off process. As aresult, the array substrate according to the present invention can beobtained by a four mask process. In addition, an electrical shortproblem between adjacent lines, i.e., the gate line 105 and the commonline 109, at the same layer, is not generated due to the groove 116through the gate insulating layer 113. This is adopted to other adjacentlines, i.e., two closely adjacent gate lines. Furthermore, since anadditional mask process is not required for the groove 116, there is noincrease in the fabricating process and the production costs. Moreover,since a laser repair process is not required to resolve the electricalshort problem, production yield is increase.

On the other hand, the dummy metal pattern 110 may be omitted. Namely,the gate line 105, the gate electrode 107, the common line 109, the gatelink line 106 except the dummy metal pattern are formed from the firstmetal layer. In this case, when the groove 116 is formed by etching theimpurity-doped amorphous silicon layer 123, the intrinsic amorphoussilicon layer 120 and the gate insulating layer 113, the substrate 101is directly exposed through the groove 116. In addition, the secondmetal layer for the data line 130, the source electrode 133 and thedrain electrode 136 contacts the substrate 101 through the groove notthe dummy metal pattern. When the electrical short problem is generatedbetween the gate line 105 and the common line 109, an electrical shortportion is removed by not only the step of forming the groove but alsothe step of forming the data line 130, the source electrode 133 and thedrain electrode 136. As a result, the electrical short problem isresolved.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An array substrate for a liquid crystal display device, comprising: first and second lines on a substrate and spaced apart from each other, the first and second lines formed of a first metallic material; a gate electrode connected to the first line; a gate insulating layer on the first and second lines and the gate electrode and including a groove, the groove exposing the substrate and positioned between the first and second lines; a semiconductor layer on the gate insulating layer and corresponding to the gate electrode; a data line crossing the first and second lines and on the gate insulating layer; a source electrode on the semiconductor layer and connected to the data line; a drain electrode on the semiconductor layer and spaced apart from the source electrode; a passivation layer on the data line, the source electrode and the drain electrode and including an opening, the opening exposing a portion of the gate insulating layer and an end of the drain electrode; and a pixel electrode positioned on the gate insulating layer and in the opening, the pixel electrode contacting the end of the drain electrode, wherein the passivation layer contacts the substrate at the groove.
 2. The array substrate according to claim 1, wherein each of the data line, the source electrode and the drain electrode is formed of a second metallic material being same as the first metallic material or being etched by an etchant for the first metallic material.
 3. The array substrate according to claim 1, wherein a width of the groove is smaller than a distance between the first and second lines.
 4. The array substrate according to claim 1, wherein a length of the groove is smaller than a distance between two adjacent data lines.
 5. The array substrate according to claim 1, wherein the pixel electrode has a thickness smaller than the passivation layer.
 6. The array substrate according to claim 1, further comprising: a gate link line on the substrate and connected to an end of the gate line, wherein the gate insulating layer further includes a link contact hole exposing the gate link line; a gate pad on the gate insulating layer and contacting the gate link line through the link contact hole; a data pad on the gate insulating layer and connected to an end of the data line; and a gate pad electrode and a data pad electrode on the passivation layer, wherein a gate pad contact hole exposing the gate pad and a data pad contact hole exposing the data pad are formed through the passivation layer, and the gate pad electrode and the data pad electrode respectively contact the gate pad and the data pad through the gate pad contact hole and the data pad contact hole. 